The present invention relates to a penetrator assembly for establishing communication between a tubing hanger and a surrounding christmas tree or wellhead housing. More particularly, the invention relates to such a penetrator which comprises at least one retractable member and a valve member which, upon retraction of the retractable member, will sever a data line extending from the tree or wellhead housing, through the penetrator assembly, and into the tubing hanger.
Monitoring of downhole conditions has traditionally been accomplished with electronic transducers. These are sited at regular intervals along the length of the tubing and also at reservoir level, and are used to monitor parameters such as temperature, pressure and stress levels. The disadvantage of this system is the difficulty in maintaining electrical contact in the environment which is being monitored. This can lead to erroneous information on the downhole situation, and therefore lost time.
More recently, the advent of fiber optic diagnostic systems has substantially reduced this disadvantage. A fiber optic loop is fed downhole, and a signal sent and received at opposing ends. The generated and received signals are compared using a decoder, and the downhole conditions are interpreted, providing a faster, more reliable monitoring method.
The monitoring line must pass downhole from outside the well, usually through the christmas tree to inside the tubing hanger, such that pressure integrity is not compromised. Any such access into the well requires a gas tight pressure seal to be set up around the line. During operations such as workovers, the fiber optic line presents a further problem. The line is usually routed through the completion in a way that will cause it to be broken if the tubing hanger and attached tubing string is pulled. The time involved in retrieving the line prior to pulling the tubing hanger renders the option of line retrieval impractical. Retrieval also presents another problem in that the line feed path must be sealed afterwards.
In accordance with the present invention there is provided a pressure barrier for retaining well fluid separate from a surrounding environment, characterized in that the barrier comprises a valve through which a data line extends between the environment and the well interior, the valve being sealably closable to sever the line. The line itself is relatively inexpensive to replace, and any pieces of sheared line remaining downhole can be flushed out before installation of a replacement line. When closed, the valve will maintain the pressure integrity of the barrier. This system has the benefit of minimizing costs, since it is much faster and easier to shear the line and seal its path into the well simply by closing the valve, than it is to retrieve the line and then plug its vacated path into the well. Although the invention is beneficial for use with fiber optic lines, it may also be employed in conjunction with any relatively small diameter line (electrical, optical or other) capable of being severed by a valve and which is relatively inexpensive to replace.
The valve may comprise a valve housing having a valve closure member movably received therein, the line passing through aligned apertures in the housing and closure member, movement of the closure member to close the valve causing the apertures to move out of alignment and sever the line.
Preferably the pressure barrier comprises a penetrator incorporating the valve and movable between a position in which the penetrator engages an interior well component and a position in which the penetrator is disengaged from the component, allowing the component to be pulled from or installed in the well. The component may include a further valve through which the line passes. Preferably the or each valve is closeable upon disengagement of the penetrator from the component. For example, the valve or valves may comprise poppet valves having sufficient closure bias to sever the line. The valves may be arranged to be opened by engagement of the penetrator with the component.
The invention and its preferred features and advantages are described below with reference to an illustrative embodiment shown in the drawings.